Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/140



The proofs which the deep vallies, separating the detached eminences characteristic of this system, afford of their formation by an agent which has excavated and scooped out as it were portions of the solid strata, have been most ably and clearly detailed by Dr. Richardson in the appendix to the Statistical Survey of Antrims The general appearances he describes are common (it should be remarked) to the vallies of all countries composed of nearly horizontal strata; but one phenomenon, as stated by him, seems almost peculiar to Antrim, namely, that the materials so removed have been entirely carried off, leaving no traces behind them. This circumstance seems to incline Dr. Richardson to consider the agent which has acted in the manner described, as some unknown and undiscoverable cause, and to hesitate in receiving the common and surely probable opinion which regards diluvial currents as presenting a satisfactory solution; but it must be remembered that the solitary instances he adduces can never weigh against the great majority of cases in which the fragments of the rocks so destroyed not only occur in abundance where they might be expected, but exhibit the most unequivocal marks of their having experienced the action of agitated waters. He who has examined the valley of the Thames from its source downwards can be at no loss for illustrations of these positions, the vast deposits of waterworn debris of oolite which this valley where it traverses the range of hills occupied by this rock, and those of flint pebbles where it crosses the chalky hills. or the Chilterns, will instantly occur to his mind. It is surely more philosophical to suppose that the violence of the currents has swept away the debris of the Antrim excavations into Lough Neagh on the one side, and into the sea on the other, than that these excavations owe their origin to some unknown cause, distinct from that which appears to have produced all others.